There is an unbelievable amount of format comparison going on on various sites. I'm baffled! You quite simply cannot compare two different formats - for the simple reason that to do a valid comparison of an identical 'real world' (not test) subject. And obviously this isn't possible because you can't use the same lens so..... etc., etc., etc..
So why not point out the strengths and weaknesses of each format/camera. Yes, technology has moved on from the introduction of the 1DS (my own camera) and the 40D, and yes the 5D has some attributes which may mean that it is a far more appropriate camera in many circumstances to a 1DS, BUT....
All will take good images!
I would not personally change from my 1DS to a 40D (or 5D come to that) for innumerable reasons - not least because I like many of its (old) attributes and have learned to deal with many of its weaknesses (and yes it does have a lot). But this vague notion of better Image Quality bugs me. This really depends on what you are trying to achieve. To explain what I mean in an analogy, buying a supercar to drive half a mile to the shops won't make you a better driver and is unlikely to have substantial benefits over using a supermini - in fact it might have drawbacks. Photo equipment choice should be about using the appropriate tool for the job and has many more facets to it than simply newer technology and the vague notion of Image Quality. As another example, I could buy a new Nikon D3 when it is available - its spec would be fine for me and as an ex-Nikon user I would probably like its ergonomics and handling, but unless Nikon bring out a lens similar to my beloved 24/1.4 then there would be no point in me changing because this is my wide-angle of choice and I use it heavily in a variety of shooting situations each for very good reason.
Choosing between a 1DS and 40D should encompass the lens choice, specification and availability as well as a comparison of the strengths and weaknesses of each camera, and not least, what it is to be used for, but to simply get hung up on one detail is, IMHO, missing the point.
As stated in the last post, batteries are not brilliant on the 1DS - I have a load of them in varying states of power loss!